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Solar Energy, the Atmosphere and Biomes

Solar Energy, the Atmosphere and Biomes. Earth-Sun Relationships. Earth’s Motions Earth has two principal motions—rotation and revolution Earth’s Orientation (tilt) Seasonal changes occur because Earth’s position relative to the sun continually changes as it travels along its orbit.

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Solar Energy, the Atmosphere and Biomes

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  1. Solar Energy, the Atmosphere and Biomes

  2. Earth-Sun Relationships Earth’s Motions • Earth has two principal motions—rotation and revolution Earth’s Orientation (tilt) • Seasonal changes occur because Earth’s position relative to the sun continually changes as it travels along its orbit

  3. Energy Transfer as Heat Three mechanisms of energy transfer: Conduction is the transfer of heat through matter by molecular activity Convection is the transfer of heat by circulation within a substance. Radiation is the transfer of energy (heat) through space by electromagnetic waves that travel out in all directions

  4. What Happens to Solar Radiation? • Scattering: • Clouds, dust and gas reflect and bend light rays; light rays are sent out in all directions • Causes sky to appear blue (blue light is more easily bent) • Sunsets appear red because longer wavelengths (red) are able to reach the surface (we are looking through more atmosphere on the horizon)

  5. What Happens to Solar Radiation? • Reflection: • 20% of solar radiation is absorbed by the atmosphere • 50% is absorbed by the surface • 30% is reflected back into space • Albedo: fraction of solar radiation that is reflected back into space. • Earth’s albedo is 0.3

  6. What Happens to Solar Radiation? Absorption & Infrared Energy: • As the surface absorbs radiation, it heats up and releases IR radiation • IR radiation is trapped by water vapor and CO2 in the atmosphere • This process is called the greenhouse effect

  7. What Happens to Solar Radiation? Why Temperatures Vary Factors include: • latitude • heating of land and water, • altitude • geographic position • cloud cover • ocean currents

  8. Prevailing winds pick up moisture from an ocean. On the windward side of a mountain range, air rises, cools, and releases moisture. On the leeward side of the mountain range, air descends, warms, and releases little moisture. Fig. 7-7, p. 145

  9. Elevation Mountain ice and snow Tundra (herbs, lichens, mosses) Coniferous Forest Deciduous Forest Latitude Tropical Forest Coniferous Forest Tundra (herbs, lichens, mosses) Deciduous Forest Tropical Forest Polar ice and snow Stepped Art Fig. 7-9, p. 147

  10. Properties of Air Density • At constant pressure, warm is less dense than cold air • Therefore, warm air rises, cold air sinks

  11. Properties of Air Water Vapor Capacity • Warm air has a higher capacity for water • Specific humidity is a measure of the amount of water vapor in the air • Relative humidity is a ratio of the amount of water present to the capacity • If RH = 100%, saturation occurs • Dew point is the temperature at which saturation occurs

  12. Properties of Air Adiabatic Heating and Cooling • As air rises in the atmosphere rises, P ↓, air expands and cools • As air sinks toward the surface, P ↑, air volume ↓ and warms

  13. Properties of Air Latent Heat Release • As the sun warms surface water, it absorbs and stores energy as it evaporates • As water vapor in the atmosphere condenses, it releases this stored (latent) energy

  14. Factors Affecting Wind • Wind is the result of horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure • The unequal heating of Earth’s surface generates pressure differences • Three factors combine to control wind: pressure differences, the Coriolis effect, and friction

  15. Factors Affecting Wind Pressure Differences • A pressure gradient is the amount of pressure change occurring over a given distance • Isobars are lines on a map that connect places of equal air pressure • Closely spaced isobars indicate a steep pressure gradient and high winds

  16. Factors Affecting Wind Coriolis Effect • The Coriolis effect describes how Earth’s rotation affects moving objects. • In the Northern Hemisphere, all free-moving objects or fluids, including the wind, are deflected to the right of their path of motion. • In the Southern Hemisphere, they are deflected to the left

  17. Factors Affecting Wind Friction • Friction acts to slow air movement, which changes wind direction • Jet streams are fast-moving rivers of air that travel in a west-to-east direction (120 - 240 km/hour); little friction

  18. Global Winds • Convection Cells: • Warm air rises near the equator • Cooler air from the north replaces it at the surface • The warm air that rose flows northward and downward as it cools • The convection cells are called Hadley Cells

  19. LOW PRESSURE HIGH PRESSURE Heat released radiates to space Condensation and precipitation Cool, dry air Rises, expands, cools Falls, is compressed, warms Hot, wet air Warm, dry air Flows toward low pressure, picks up moisture and heat LOW PRESSURE HIGH PRESSURE Moist surface warmed by sun Fig. 7-4, p. 143

  20. Global Winds & Biomes

  21. Moist air rises, cools, and releases moisture as rain Polar cap Arctic tundra Evergreen coniferous forest 60° Temperate deciduous forest and grassland Desert 30° Tropical deciduous forest Equator 0° Tropical rain forest Tropical deciduous forest Desert 30° Temperate deciduous forest and grassland 60° Polar cap Fig. 7-6, p. 144

  22. Fig. 7-8, p. 146

  23. Cold Polar Tundra Subpolar Temperate Coniferous forest Decreasing temperature Desert Grassland Deciduous forest Tropical Chaparral Hot Desert Savanna Rain forest Wet Dry Tropical seasonal forest Scrubland Decreasing precipitation Fig. 7-10, p. 147

  24. Biomes • Tundra • Boreal forest • Temperate rainforest • Temperate seasonal forest • Woodland/shrubland • Tropical rainforest • Subtropical desert

  25. Currents

  26. Fig. 7-2, p. 142

  27. Thermohaline Circulation Warm, less salty, shallow current Cold, salty, deep current Fig. 7-5, p. 143

  28. El Nino Southern Oscillation • 3 – 7 year cycle • Surface currents in the tropical Pacific reverse direction (trade winds weaken) • Warm water moves westward, suppressing the upwelling of nutrients off the coast of S. America • Fish populations are hurt • Global impact: cooler, wetter conditions in SE US; drier in S Africa, SE Asia

  29. Biomes For your biome PowerPoint: • Describe vegetation and animal life • Describe general climate; include global location(s) • Include a climate diagram (annual temperature & rainfall) • 3 – 5 slides; keep it simple!

  30. Categorized by salinity, depth, water flow Aquatic biomes

  31. Streams & Rivers • Flowing fresh water • Originate from springs or runoff • Rapid flow = few producers; rely on terrestrial biomes (leaves) • Slow rivers: nutrients settle and provide substrate for plants • Rapids: high O2 content

  32. Lakes and Ponds • Contain standing water • Divided into distinct zones: • Littoral Zone: shallow area of soil & water near shore; rooted plants, photosynthesis • Limnetic Zone: rooted plants cannot survive; phytoplankton photosynthesize • Profundal Zone: deep lakes; low O2 due to decomposers; muddy bottom: benthic zone

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